Nitrofuryl isoxazole derivatives

ABSTRACT

THE COMPOUNDS ARE OF THE CLASS OF NITROFURYL ISOXAZOLE DERIVATIVES, AND MORE PARTICULARLY 3-(5-NITRO-2-FURYL)-5AMINO ISOXAZOLE FURTHER SUBSTITUTED IN 4-POSITION. THE COMPOUNDS ARE USEFUL AS ANTIMICROBIAL, ANTHELMINTIC AND GROWTH-PROMOTING AGENTS. ILLUSTRATIVE EMBODIMENTS ARE 3-(5-NITRO-2-FURYL) - 4 - CHLOROCARBONYL-5-AMINO ISOXAZOLE AND 3-(5-NITRO - 2 - FURYL)-4-DIMETHYLCARBAMOYL-5-AMINO ISOXAZOLE.

United States Patent 3,562,286 NITROFURYL ISOXAZOLE DERIVATIVES William Hoyle, Bramhall, and Graham Arton Howarth,

Handforth, England, assignors to Geigy Chemical Corporation, Ardsley, N.Y., a corporation of New York No Drawing. Filed Feb. 12, 1968, Ser. No. 704,570 Claims priority, application Great Britain, Feb. 15, 1967, 7,289/67 Int. Cl. C07d 99/02 US. Cl. 260307 13 Claims ABSTRACT OF THE DISCLOSURE The compounds are of the class of nitrofuryl isoxazole derivatives, and more particularly 3-(5-nitro-2-furyl)-5- amino isoxazole further substituted in 4-position. The compounds are useful as antimicrobial, anthelmintic and growth-promoting agents. Illustrative embodiments are 3-(5-nitro-2-furyl) 4 chlorocarbonyl-S-amino isoxazole and 3-(5-nitro 2 furyl)-4-dimethylcarbamoyl-S-arnino isoxazole.

DETAILED DISCLOSURE The present invention relates to substituted heterocyclic compounds, and in particular to nitrofuryl derivatives of isoxazoles.

According to the present invention, there is provided a 5-nitro-2-furyl-isoxazole having the Formula I i L ozNlo CON\ O NH2 methods and compositions containing a compound of the above-mentioned Formula I for effecting antimicrobial, particularly, antibacterial, antifungal, antiviral and coccidiostatic, and anthelmintic and growth-promoting activities in warm-blooded animals, especially mammals. More particularly, the method of effecting antimicrobial, especially antibacterial, antifungal, antiviral and coccidiostatic, anthelmintic and growth-promoting activities in mammals is concerned with administering a compound as defined in Formula I in therapeutic doses. Moreover the present invention relates to intermediates of Formula 1.

According to this invention, the scope of the substituents as defined in the above-mentioned formula may be characterized as follows:

The term lower alkyl as used herein alone or in lower alkenyl, cycloalkyl, and lower alkoxycarbonyl means straight or branchedlalkyl chains of the general formula C H wherein m represents an integer of 6 or less. These terms may be further illustrated as follows:

If either or both of the groups R and R is alkyl, each of these groups may be, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, secondary butyl or tertiary butyl. If either or both of the groups R and R is an alkyl group substituted by a halogen substituent, the halogen may .be fluorine or iodine but is preferably chlorine or bromine. If either or both of the groups R and R is an alkyl group which is hydroxy-, alkoxyor halogen-substituted, preferably the alkyl group contains one or two halogen, alkoxy or hydroxy substituents. If either or both of the groups R and R is alkenyl, this may be, for example, allyl, 2-methallyl, Z-butenyl (crotyl) or 3-butenyl. If either or both of the symbols R and R is cycloalkyl, this may be cyclopentyl but is preferably cyclohexyl. If either of the symbols R or R is an alkoxycarbonyl group, the alkyl portion of the carbalkoxy group may be, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl or tertiary butyl.

Particularly preferred compounds of the invention have the Formula I wherein R and R are the same and especially when each is alkyl containing from 1 to 4 carbon atoms, or alkyl substituted by hydroxy or lower alkoxy.

The 5-nitro-2-furyl-isoxazole of Formula I may be prepared by reacting a reactive functional derivative of a carboxylic acid of a S-nitro-furyl-isoxazole compound of Formula II O2N CO-OH 0 Lu j:

NH o 2 (II) with a compound having the Formula III R2 (III) or with a derivative capable of producing the compound of Formula III under the conditions of the reaction.

The reactive functional derivative of an acid of a substituted S-nitro-furyl-isoxazole compound of Formula II is a compound capable of reacting with the reactant of Formula III to produce the desired S-nitro-furyl-isoxazole of Formula I. The compound of Formula II may be, for instance, a 5-nitro-2-furyl-isoxazole acid halide having the Formula Ila NHz the halogen being preferably chlorine or bromine. The reaction with the acid halide is conveniently carried out in the presence of an organic solvent which is substantially inert under the conditions of the reaction. The reaction may .be carried out at a temperature in the range of from 10 C. to the boiling point of the mixture under reflux. A conventional hydrogen halide binding agent may advantageously be present in the reaction mixture; and, if desired, instead of employing an added base as binding agent, the process may be effected using an excess of the reactant of Formula III over the stoichiometric equivalent of the acid halide of Formula 1141.

Other suitable reactive functional derivatives of the compound of Formula II which may be used in the process of the invention comprise anhydrides and mixed anhydrides in the presence of an acid binding agent, free acids in the presence of agents combining with water, and azides and activated esters, for example cyanomethyl esters and p-nitrophenyl esters. The acid binding agent used in the process may be, for example, sodium or potassium carbonate or bicarbonate dispersed in an aqueous-organic or organic medium or triethylamine, pyridine or other tertiary organic base dispersed in dioxan, tetrahydrofuran, acetone, chloroform or other organic media. The agent combining with water may be, for example, dicyclohexyl carbodiimide.

The expression mixed anhydrides signifies firstly anhydrides mixed with anhydrides of lower alkanoic acids, especially acetic acid, and secondly anhydrides which are carbonic acid semi-esters, produced for instance by reacting the monocarboxylic acid of Formula II with the benzyl, p-nitrobenzyl, isobutyl, ethyl or methallyl esters of chloroformic acid.

The present invention also comprises the -nitro-2- furyl-isoxazole acid halides of Formula 11a in which the halogen is chlorine or bromine, these compounds being novel substances.

For example the starting materials of Formula IIa may themselves be produced by reacting the corresponding carboxylic acid derivative having the Formula II with a halogenating agent containing the corresponding halogen. Examples of preferred halogenating agents include thionyl chloride and thionyl bromide. If a thionyl halide is used, it may, if desired be in the form of a complex with dimethyl formamide.

The carboxylic acid derivative of Formula II is also a novel compound and is comprised within the present invention. The compound may be conveniently produced by hydrolysing a tertiary alkyl ester having the Formula IV O2N J1 00.0114

wherein R is a tertiary alkyl group containing from four to twelve carbon atoms, with an acid hydrolysing agent.

The tertiary ester of Formula IV is preferably the tertiary butyl ester, but may also be the tertiary octyl or tertiary dodecyl ester. The hydrolysis is carried out in the presence of an acid hydrolysing agent, for example an aqueous formic acid solution containing a major proportion of formic acid. The product of the hydrolysis may be purified, if desired, but conveniently the crude product containing the compound of Formula II is reacted with the halogenating agent.

Although the compounds of the present invention have been ascribed the Formula I above, they may also be represented by either or both of the following tautomeric Formulae Ia and lb, and any specific compound of the invention may occur in any of these tautomeric forms or as a mixture of two or all thereof.

oar-m LCCHCON/ 0 II I In this specification, however, the compounds are regarded for purposes of clarity as having the Formula I and are 4 thus described and exemplified as being nitrofuryl-isoxazole derivatives.

The compounds of the invention have useful pharmacological and, in particular, antimicrobial properties, being valuable antibacterial, antifungal, antiviral, anthelminthic, coccidiostatic or growth-promoting agents for external or internal use in warm-blooded animals, particularly mammals. The compounds are particularly valuable in the treatment of infections of the intestinal or urinary tract. The compounds may also be used to protect an organic material susceptible to bacterial, fungal or other microbial deterioration by contacting with, impregnation in or other- Wise treating the material with the compounds.

Accordingly, the invention also provides compositions comprising an antimicrobially effective proportion of a 5-nitro-2-furyl-isoxazole of Formula I and a pharmaceutically acceptable solid carrier or liquid diluent.

The pharmaceutical compositions according to the invention contain at least one compound of general Formula I as active substance together with a conventional pharmaceutical carrier. The type of carrier actually used depends to a great extent on the intended application: for external use, for example in disinfecting healthy skin, disinfecting wounds and in treating dermatoses and affections of the mucous membranes caused by bacteria; ointments, powders and tinctures are used in particular. The ointment bases may be anhydrous, for instance they can consist of mixtures of wool fat and soft paraflin, or they can consist of aqueous emulsions in which the active substance is suspended. Suitable carriers for powders are, for instance, rice starch and other starches; the bulk weight of the carriers may be made lighter, if desired, for example by adding highly dispersed silicic acid, or may be made heavier by adding talcum. The tinctures may con tain at least one active compound of the Formula I in aqueous ethanol, in particular 45% to ethanol, to which 10% to 20% of glycerol may be added, if desired. Solutions prepared from polyethylene glycol and other conventional solubility promoters, and also optionally, from emulsifying agents, may be used with particular advantage in disinfecting healthy skin. The content of active ingredient in pharmaceutical compositions for external application is preferably in the range of from 0.1% to 5%.

Gargles or concentrates for their preparation, and tablets for slow dissolution in the mouth, are suitable for the disinfection of the mouth and throat. The former are preferably prepared from alcoholic solutions containing 1% to 5% of active substance to which glycerol or flavorings may be added. Lozenges, that is solid dosage units, preferably have a relatively high content of sugar or similar substances and a relatively low content of active substance, for instance 0.2% to 20% by weight, as well as the usual conventional additives such as binding agents and flavorings.

Solid dosage units, in particular tablets, dragees (sugar coated tablets) and capsules, are convenient for use in intestinal disinfection and for the oral treatment of urinary tract infections. These units preferably contain from 10% to of the compound of the general Formula I. Tablets and dragee cores are produced by combining the compounds of the general Formula I with solid, pulverulent carriers such as lactose, saccharose, sorbitol, maize starch, potato starch or amylopectin, cellulose derivatives or gelatines, preferably with the addition of lubricants such as magnesium or calcium stearate or polyethylene glycols of suitable molecular weight. Dragee cores may then be coated, for example with concentrated sugar solutions which can also contain gum arabic, talcum and/or titanium dioxide, or they may be coated with a lacquer dissolved in volatile organic solvents or mixture of solvents. Dyestulfs can be added to these coatings, for instance to differentiate between varying dosages. Soft gelatine capsules and other closed capsules consist, for example, of a mixture of gelatines and glycerol and may con- Muench: Am. J. Hyg. 27, 493 (1938)] for 3-(5-nitro-2- furyl)-4-dimethylcarbamoyl-S-amino isoxazole was about 40 mg./kg.

The antimicrobial activity was also determined by ascertaining the diameter of zones in which the growth of bacteria was inhibited in agar medium. The agar medium was pretreated with a suspension of Escherichia coli, Klebsiella pneumoniae, Salmonella typhi, or Staphylococcus aureus.

Diameter of zone inhibition in mm.

2 Escherl- Klebsiella Salmonella Staphylococchza COZZ, pneumonia, typ cus aureus,

Compound tested NCTA 86 NTC 7242 NCTC 8384 NCTC 7447 3-(5-nitro-2-tury1)-4-dimethy1carbamoy1-5-amino isoxazole 56 36 3-(5-nitro-2-furyl)-4-allylcarbamoy1-5-a111ino isoxazole 63 34 24 32 eral Formula I can be present as sole active ingredients or they can also be combined with other known pharmacologically active, and especially antibacterial and/or antimycotically or other antimicrobially active substances, for example to broaden the range of application. They can be combined for example, with 5,7-dichloro-2-methyl- 8-quino1inol or other derivatives of S-quinolinol, with sulfamerazine or sulfafurazole or other derivatives of sulfanilamide, with chloramphenicol or tetracycline or other antibiotics, with 3,4,S-tribromosalicylamide or other halogenated salicylanilides, with halogenated carbanilides, with halogenated benzoxazoles or benzoxazolones, with polychlorohydroxy-diphenylmethanes, with halogen-dihydroxy-diphenyl sulfides, with 4,4-dichloro-2-hydroxy-diphenylether or 2,4,4-trichloro-2-hydroxydiphenylether or other polyhalogenhydroxy-diphenylethers, or with bactericidal quaternary compounds or with certain dithiocarbamic acid derivatives such as tetramethylthiuram disulfide. Also carriers which themselves have favorable pharmacological properties may be used, for instance sulfur as a powder base or zinc stearate as a component of ointment bases.

The invention also provides a method of protecting an organic material susceptible to bacterial, fungal or other microbial attack which comprises treating the material with a 5-nitro-2-fury1-isoxazole of Formula I. The organic material may be, for instance, a natural or synthetic polymeric material, a proteinaceous or carbohydrate substance, or a natural or synthetic fibre or textile material formed therefrom.

The toxicity of the compounds of the present invention is low: for instance, subchronical toxicity tests proved that amounts of more than 300 mg./ kg. of 3-(5-nitro-2-furyl)- 4-dimethylcarbamoyl-S-amino isoxazole were tolerated by mice on oral administration without causing undesirable side effects. Also the oral administration of 3-(5-nitr0-2- furyl -4-di ,B-hydroxyethyl carbamoyl-S-amino isoxazole to mice were tolerated up to doses higher than 300 mg./ kg. in subchronic tests.

The antimicrobial activity was studied on the following bacteria and fungi by determining the inhibiting concentration in p.p.m. in in vitro experiments:

3- (5-nitro-2-furyl -4-allyl- In in vivo tests, 3-(5-nitro-2-furyl)-4-dimethylcarbamoyl-S-amino isozazole proved to be effective for combatting staphylococci in mice when administered orally. The ED [determined according to L. I. Reeds and H.

The compounds of the invention may be used in warmblooded animals, particularly mammals, in form of pharmaceutical compositions containing the compounds in admixture or conjunction with a pharmaceutical organic or inorganic, solid or liquid carrier for oral, rectal, parenteral, or topical administration. The preferred routes of administration are the oral and topical routes. The total daily doses for mammals can vary from about 0.5 mg./ kg. to about 300 mg./kg., preferably about 1 mg./ kg. to about 100 mg./kg., depending on the mammal and condition.

The following examples further illustrate the present invention without limiting the scope thereof in any way. Percentages are expressed by weight unless otherwise stated. The temperatures are given in degrees centigrade.

EXAMPLE 1 A mixture of 30 g. of 3-(5-nitro-2-furyl)-4-amino-5- tert-butoxycarbonyl-isoxazolev and 300 ml. of aqueous formic acid was heated at 70 for 10 minutes. After cooling, the crystalline precipitate was collected, washed with water and recrystallised from a mixture of acetone and water.

The product was 3 (5 nitro 2 furyl)-4-carboxy-S- amino-isoxazole, having melting point 237, with decomposition.

EXAMPLE 2 A mixture of 82 g. of 3-(5-nitro-2-furyl)-4-carboxy-5- amino-isoxazole and 1400 ml. of thionyl chloride was heated under reflux for 5 hours. After cooling, the crystalline precipitate was collected, washed with anhydrous ether and dried.

The product was 3-(5-nitro-2-furyl)-4-chlorocarbonyl- S-amino-isoxazole, having melting point 199.

EXAMPLE 3 To a solution of 12.9 g. of 3-(5-nitro-2-furyl)-4-chlorocarbonyl-5-arnin0-isoxazole dissolved in 500 ml. of ethyl acetate was added 7.3 g. of diethylamine and the mixture was allowed to stand.

After concentration of the mixture by evaporation, the crystalline precipitate was collected, washed with water and recrystallised from a mixture of dimethylformamide and water. The product was 3-(S-nitro-Z-furyl)-4-diethylcarbamoyl-S-amino-isoxazole, having melting point 208 with decomposition.

EXAMPLE 4 The procedure described in Example 3 was carried out using the molecular equivalent of dimethylamine gas dissolved in 25 ml. of ethyl acetate as starting material instead of diethylamine, the reaction conditions being otherwise essentially the same.

The product was 3-(5-nitro 2 furyl) 4 dimethylcarbamoyl-S-amino-isoxazole, having melting point 208 with decomposition.

7 EXAMPLE 5 The procedure described in Example 3 was carried out using the molecular equivalent of diallylamine as starting material instead of diethylamine, the reaction conditions being otherwise essentially the same.

The product was 3 (5 nitro 2 furyl)-4-diallyl-carbamoyl-S-arnino-isoxazole, having melting point 178.

EXAMPLE 6 The procedure described in Example 3 was carried out using the molecular equivalent of di-isopropylamine as starting material instead of diethylamine, the reaction conditions being otherwise essentially the same.

The product was 3-(5-nitro 2 furyl)-4-di-isopropylcarbamoyl-S-amino-isoxazole, having melting point 181.

EXAMPLE 7 The procedure described in Example 3 was carried out using the molecular equivalent of ethyl N-methyl-carbamate as starting material instead of diethylamine, the reaction conditions being otherwise essentially the same.

The product was 3 (5 nitro-2-furyl)-4-(N-methyl-N- ethoxy-carbonyl-carbamoyl)-5-amino-isoxazo1e.

EXAMPLE 9 The procedure described in Example 3 was carried out using the molecular equivalent of allylamine as starting material instead of diethylamine, the reaction conditions being otherwise essentially the same.

The product was 3-(5-nitro-2-furyl)-4-ally1carbamoyl- 5-amino-isoxazole, having melting point 164.

EXAMPLE 10 The procedure described in Example 3 was carried out using the molecular equivalent of bis-(2-methoxyethyl)- amine instead of diethylamine, the reaction conditions being otherwise essentially the same.

The product was 5-amino-4-[bis (2 methoxyethyl)]- carbamoyl-3-(5-nitro 2-furyl)-isoxazole, having melting point 134.

EXAMPLE 11 By carrying out the procedure described in Example 3 using the molecular equivalent of either of the following amine reactants as starting material instead of the diethylamine there used:

bis- 2-chloroethyl) -amine dicyclohexylamine the reaction conditions being otherwise essentially the same, the folowing products are obtained respectively:

-amino-4- [bis- 2-chloroethyl) ]-carbamoyl-3- (5 nitro-2-furyl -isoxazole,

S-amino-4-dicyclohexylcarbamoyl-3- 5 -nitro-2- furyl) -isoxazole.

EXAMPLE 12 250 g. of 3-(5-nitro-2-furyl)-4-dimethylcarbamoyl-5- amino isoxazole, 175.8 g. of lactose, and 169.7 g. of potato starch are mixed, the mixture is moistened with an alcoholic solution of g. of stearic acid and granulated through a sieve. After drying, 160 g. of potato starch,

200 g. of talcum, 2.5 g. of magnesium stearate and 32 g. of colloidal silicon dioxide are mixed in and the mixture is pressed into 10,000 tablets each weighing mg. and containing 25 mg. of 3 (5 nitro 2 furyl)-4-dimethylcarbamoyl-S-amino isoxazole. If desired, the tablets can be grooved to enable better adaptation of the dosage instructions.

EXAMPLE 13 A granulate is produced from 250 g. of 3-(5-nitro-2- furyl)-4-di(fi-hydroxyethyl)carbamoyl-S-amino isoxazole, 175.9 g. of lactose and the alcoholic solution of 10 g. of stearic acid. After drying, the granulate is mixed with 56.6 g. of colloidal silicon dioxide, 165 g. of talcum, 20 g. of potato starch, and 2.5 g. of magnesium stearate and 10,000 dragee cores are pressed from the mixture. These are first coated with an alcoholic solution of 6 g. of shellac, then with a concentrated syrup made from 502.28 g. of crystallized saccharose, 10 g. of gum arabic, 0.22 g. of dyestuff and 1.50 g. of titanium dioxide, and then dried. The dragees obtained each weigh mg. and contain 25 mg. of 3-(5-nitro-2-furyl)-4-di(B-hydroxyethyl)carbomyl-S-amino isoxazole.

EXAMPLE 14 10 mg. to 50 mg. of 3-(5-nitro-2-furyl)-4-dimethylcarbamoyl-S-amino isoxazole are introduced into a twopiece gelatine No. 1 capsule.

What is claimed is:

1. A compound of the formula i GON u...

wherein R and R each independently are lower alkyl of from 1 to 4 carbon atoms; lower alkyl of from 1 to 4 carbon atoms substituted by hydroxy, lower alkoxy or halogen; lower alkenyl of from 3 or 4 carbon atoms; cycloalkyl with 5 or 6 carbon atoms; or lower alkoxycarbonyl wherein the alkyl contains from 1 to 4 carbon atoms; or

when R is lower alkenyl with 3 or 4 carbon atoms,

R is hydrogen.

2. A compound as defined in claim 1 wherein R and R each independently are lower alkyl with 1 to 4 carbon atoms or lower alkyl with 1 to 4 carbon atoms substituted by hydroxy.

3. A compound as defined in claim 1 wherein R and R each independently are lower alkyl with 1 to 4 carbon atoms substituted by lower alkoxy.

4. A compound as defined in claim 1 wherein said compound is 3-(5-nitro-2-furyl)-4-diethylcarbamoyl-S-aminoisoxazole.

5. A compound as defined in claim 1 wherein said compound is 3 (5 nitro 2 furyl)-4-dimethylcarbamoyl-5- amino isoxazole.

6. A compound as defined in claim 1 wherein said compound is 3-(5-nitro-2-furyl)-4-diallylcarbamoyl-5-amino isoxazole.

7. A compound as defined in claim 1 wherein said compound is 3 (5-nitro-2-furyl)-4-di-isopropylcarbamoyl-5- amino isoxazole.

8. A compound as defined in claim 1 wherein said compound is 3-(5-nitro 2 furyl)-4-di(,8-hydroxyethyl)carbamoyl-S-amino isoxazole.

9. A compound as defined in claim 1 wherein said compound is 3 (5-nitro-2-furyl)-4-(N-methyl-N-ethoxycarbonyl-carbamoyl)-5-amino isoxazole.

10. A compound as defined in claim 1 wherein said OzN- compound is 3-(5 nitro 2 furyl)-4-allylcarbamoyl-5- References Cited amino isoxazole- M t t t 1. h Ph B 11. 1. 1

11. A compound as defined in claim 1 wherein said a gg ai c em arm u v0 pp compound is 3-fi5-nifro-2-furyn-4-[b1$(2-methXYethY1)1 Morrison et 211., Organic Chemistry (Allyn and Bacon, carbamoyl-5 ammo lsoxazole. D 5 Inc. Boston, 1961),

12. S-(S-mtro-Z-furyl)-4-carboxy11c ac1d-5-am1no lsoxazo1e ALTON D. ROLLINS, Prnnary Exammer 13. 3-(5-nitro-2-furyl)-4-chlorocarbonyl-S-amino isoxa- US. Cl. X.R, zole. 424228, 229, 272 

